The present invention relates, in general, to a bumper of a motor vehicle.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Bumpers for motor vehicles are typically arranged across the front and rear of a motor vehicle to absorb energy caused by an impact and thus to minimize damage to the actual support structure of the motor vehicle. A bumper typically includes a cross member which can be fixed transversely to the side rails of the motor vehicle frame, with crash boxes being placed in-between. The cross member is provided to deflect the energy, generated in the event of an impact, into the crash boxes which convert the impact energy into deformation work.
A multiplicity of differently arranged bumpers is well-known. Bumpers must meet official regulations as well as the demands established by consumer protection agencies to protect passengers. In addition, insurers have established classification tests (RCAR Research Council for Automobile Repairs, GDV Gesamtverband der Deutschen Versicherungswirtschaft [Association of German Insurers]), which must also be met.
There is increasingly a desire to build bumpers from components that are best suited to one another in order to realize a defined energy absorption. Moreover, there is also increasingly a demand for reducing CO2 emission by providing a lightweight construction when designing vehicles. It is hereby important to effect a good crash behavior while still constructing the bumper lightweight.
Cross members and crash boxes are joined together to date through material union or by using screws, bolts or rivets. When accessibility to the components is from one side, the cross members and crash boxes can be joined together through direct bolting or blind riveting. Common to all these joining techniques is the need for prepunching of holes in the components. This is complex, expensive, and the connection elements are comparably heavy. Another approach, disclosed in international publications WO 2007/082714 A1 or WO 2008/125312 A1, involves the use of nails to join the cross members and crash boxes to one another.
It would be desirable and advantageous to provide an improved bumper to obviate prior art shortcomings and to improve its behavior in the event of a crash while being lightweight and simple in structure and allowing application of various material pair combinations to optimize energy absorption capability.